A bumper of this kind is known from DE 10 2004 056 956 B4. The known bumper has at least two round pipes as crossmembers which are arranged one above the other in the vertical direction and are connected to one another by a plate-like bracket between the side frames (crash boxes). In this case, the bracket is provided on the front side of the pipes and welded to said pipes. Said bracket has upper and lower bent end sections which are matched to the outer shape of the pipes. The pipes are connected to the side frames by means of carrier elements which have arcuate cutouts for receiving the pipes in an interlocking manner.
The majority of collisions between passenger cars occur at speeds of below 20 km/h. This results in damage to the front and rear of the vehicle. In the past, crash repair tests with the aim of reducing the damage to passenger cars in the event of typical collisions were developed in the insurance sector. Nowadays, automobile insurers classify passenger cars according to type on the basis of these tests, amongst other things. Automobile manufacturers take this test into account when developing new models. However, minimizing the damage to a vehicle in the event of collisions requires the bumpers of the vehicles which are involved in the collision to be geometrically compatible. Since the crossmembers of the bumpers are relatively narrow and arranged at different heights, this results in it being possible that the bumpers do not meet and slip into or enter the soft regions of the other vehicle. In these cases, the repair costs can be considerably higher than in the case of vehicles of which the bumpers meet and absorb the impact energy as intended.
However, even if the bumpers get in contact, it is additionally important for the purpose of minimizing the damage to the vehicles that the backward displacement (deformation) of the crossmember of the bumper which is caused by the impact does not exceed a certain level, for example 100 mm, since otherwise the motor assembly, in particular the radiator, is damaged. To date, conventional motor vehicle bumpers have generally not been designed to meet this requirement.
A further requirement when developing new motor vehicles is to minimize the weight of the vehicle in order to reduce fuel consumption. For this reason, bumpers which are composed of aluminum are incorporated into many motor vehicles. Although these bumpers have a relatively low weight, they have the disadvantage of relatively high material costs.